The New Gastronome

Funky Beans

A Groovy Guide to 5 Coffee Fermentation Processes

Related Articles

It all started with a dark liquid shot blowing steam into my eyes. It burnt my cheeks and overwhelmed my senses. That hot, thick and bitter drink punched me in the face without any warning. It was impolite, but it made me feel euphoric and I liked it. Since that moment, my 1€ espresso shot became both an everyday ritual and a real necessity. Caffeine and its function were key to my addiction— but now coffee is a matter of taste.

I discovered speciality coffee in a little Italian town called Bra, where the real truth behind this beverage unravelled onto my tongue. Many of us drink too many cups a day, but not all cups are the same. Some are special: they make you alert and ask for your attention, these are the cups that make you wonder what is behind that taste.

The answer is the same response you might have guessed yourself. It is life, human beings, microorganisms and their relentless hunger and movement: fermentation.

A. D. V. E. R. T. I. S. I. N. G.

After many years of debate, the coffee community decided to agree on the fact that processing—and so fermentation— had a fundamental role in determining the final taste of a coffee. So let’s put a record on and try to understand what goes on in the three most common methods of fermentation: natural process, washed process and honey process.

1. Natural process

Natural process also called dry process, is the oldest and simplest method. First, coffee cherries are harvested and dried under the sun on raised beds or a clean floor. In this phase, with liquid evaporation, the cherry pulp will spontaneously start fermenting. Thanks to its porosity, the seed absorbs sugars, acids and aromatic compounds that are formed during this spontaneous fermentation.

Following fermentation, drying usually lasts two to four weeks. When the right moisture is reached, cherries are hulled removing the skin, pulp and parchment (endocarp). Since results depend on the weather, unpredicted rainfalls or lower temperatures can compromise the health of the cherry and result in undesired molds.

Many farmers, especially those with a small production, choose the natural process because of simplicity and affordability. The process wastes no water at all and needs little machinery, making it better in terms of energy and resource use. In fact, this method originated in areas, such as Ethiopia, where water access is not guaranteed.

For many years, dry processed coffees were associated with low quality and unskilled labour, but the diffusion of speciality coffee geeks brought these coffees beans new life and attention. Natural coffees will bring more body and sweetness, lower acidity and strong fruity flavors.

They can really have that extreme funk you are constantly looking for. Aaaaaah freak out!

2. Washed process

Those who enjoy a cleaner, delicate cup of coffee will look for a washed (wet) process coffee. The washed process method begins by soaking the harvested cherries in water. This step singles out floaters: unripe or low-density cherries that will be discarded.

The good fruits are then moved to depulping machines to remove skin and pulp. What remains is the coffee seed with its sugary mucilage still intact, a slimy layer mostly composed of pectin covering the parchment.

Beans are soaked again in water, where fermentation spontaneously starts and continues for 12-72 hours. This fermentation depends on water temperature and the choice of the producer. Higher temperatures will give shorter fermentation times, while longer fermentation tends to increase acidic compounds, diversity and taste complexity.

When the beans are ready, and all of the mucilage is broken up, they are rinsed again and dried on raised beds or patios. Sunlight is a great variable for drying, an important and delicate phase.

Shade-dried coffees, compared to sun-dried coffees, will take longer to be ready and will be exposed to higher dangers. Many producers take this risk of shade drying for a reason: the final coffee will be more stable and consistent throughout time.

From an average amount of 45% humidity, the seed and parchment have to be reduced to about 11% of moisture content during drying. When this level is reached, seeds get into the last phase: hulling. Here the parchment is removed, leaving the little seed naked and ready to tease buyers.

Washed processing began in South America, where rainfalls and high moisture gave the need for a method that could avoid mold problems. It is now the most common, especially for speciality grade coffees, since it is the most requested and appreciated on the market. Without a doubt, the amount of water used in this process cannot be ignored, since every 1,000 kg of green coffee produced pollutes 10,000 m3 of water.

Washed coffees usually become elegant and balanced cups, with lower bodies, light sweetness and bright acidity. They can be extremely complex. If naturals have the funk, washed coffees have the feeling of a jazzy record you would play in low lights after dinner.

3. Honey process

Honey process combines aspects from both of the previous methods. After having the skin removed, coffee beans are dried with the mucilage still intact.

The name “honey” was born in Costa Rica, due to the color and texture of the mucilage, that makes it look like the beans were soaked in honey. Depending on the amount of mucilage and pulp still left on the bean, these coffees can be categorized in yellow, red and black honey.

Yellow grade is obtained through a delicate wash, that leaves a very thin mucilage layer on the seed. Black honeys are dried with all or most of it still on, while reds are placed in between. Higher amounts of mucilage will mean longer drying times, resulting in more bacteria activity.

The variability of this processing makes it impossible to define a common profile. Coffees that result from the honey process generally have good bodies and very high sweetness, with low or sometimes muted acidity. More pulp, more sugar.

This process gives producers more influence on the final characteristics of their product. It can be bent in different directions, in the same way, that we listen to rappers articulate their verses into inventive neo-soul, R&B and lo-fi tracks. The honey process and these smooth hip-hop flows are reflections into the future.

New releases

This covers most of the fermentation processes in coffee production, but if you want to know the latest releases then you cannot stop with the classics.

Experimental processes are non-standardized fermentations that some innovative producers are trying with great results.

4. Carbonic maceration

Carbonic maceration may sound familiar to you, so if you are thinking about wine then I have to tell you it is basically the same thing. After depulping and washing, beans are put in a sealed tank and saturated with carbon dioxide. This allows the coffee to ferment anaerobically in temperature controlled water.

5. Acetic/lactic process

If your brew reminds you of your last pisco-sour or a fresh green apple, it’s because during fermentation most of the acids produced are citric and malic. A great farm in Colombia, La Palma y El Tucan, is working on signature processes that promote the development of other compounds.

Using technology, fermentation designers control parameters (pH, moisture, temperature) inside of fermentation tanks in order to create the perfect environment for the microorganisms that they want to work faster.

These coffees have unique flavours and profiles that are hard to compare to any other. Breaking unwritten rules to create new hybrids.

This is a rough overview of what happens to coffee in the world. After all, it is a matter of how you treat and process something unique and ever-changing. No fermentation and no coffee lot will ever be the same, due to the unpredictable results of interactions between entities and environments.

Coffee is the second most traded commodity in the world, and it is grown in challenging regions, where it can strongly influence the economic stability of many households involved in its production. So get to know what your barista is serving, demand transparent production chains and look for the names of people on the coffee bags you buy.

Alessio Boggero

He is from Savona and about to graduate in Gastronomic Sciences. Alessio has discovered his love for alchemy and perception altering substances, especially those in liquid form. He loves silent people and stories that shouldn’t be told. His biggest fear in life is finding out that everything he likes is corrupt and not sustainable, just like plastic.